On Wed, 20 Mar 2019 at 12:48, Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx> wrote: > + OPT_FILENAME('O', NULL, &options->orderfile, > + N_("override diff.orderFile configuration variable")), This doesn't really tell me *why* I would want to provide -O. Or put another way, there are lots of --foo-bar for overriding some baz.fooBar config item, but they're not described like this. The primary purpose of --foo-bar, at least to me, would be to solve some actual problem, like "fooing the bar", whatever that means. Gleaning at the manpage, an alternative would be "control the order in which files appear in the output", but maybe you avoided that deliberately? "provide an orderfile"? Martin